Rotatable lamps are typically supported by cantilevered spokes or support arms, often by a pair of opposed cantilevered arms. The adjustable ability of the rotatable lamps facilitates aiming illumination in different directions and servicing the lamp fixture.
However, rotatable lighting fixtures are inherently difficult to connect to a power source. Typical lamp fixtures are connected to electrical wiring at a location separate from the rotating joints to prevent the wiring from becoming frayed or cut by the joint mechanism. However, separating the wiring location and the pivotal joint limits the range of movement of the rotatable lamp to the length of exposed wire, and the exposed wire can deteriorate due to exposure to the environment. If surplus wire is left exposed between the lamp and the supports, it may become tangled from successive rotations. In addition, exposed wiring is often unsightly.
Typical lighting fixtures attempting to overcome the exposed wiring problem provide passage for the wires directly through the rotating joint. In support systems for cantilevered lamps having two support arms, the wiring often extends through one arm of the support, while the opposed arm carries an adjustable fastener, such as a threaded bolt. For lamps which carry the wiring and an adjustable fastener in the same joint, a hollow threaded bushing is often used for the dual purpose of adjustably fastening the support and housing together and providing interior passage for the electrical wiring. However, a hollow bushing has limited strength and may collapse. Further, it is difficult to thread the wiring through the small bushing into the housing, especially in large outdoor lamps. Often, it is desirable to provide adjustable fasteners on both arms of a cantilever support when the lamp housing is large and heavy to ensure a stable and secure lighting assembly.
Examples of unsightly exterior wiring on rotatable lamps are disclosed in U.S. Pat. No. 3,519,811 to Jacobs and U.S. Pat. No. 3,246,135 to Husby. U.S. Pat. No. 1,301,994 to Archer discloses a complex method of adjusting a rotatable lamp having wiring extending through a hollow bushing U.S. Pat. No. 4,722,502 to Mueller et al. discloses a dual armed support having one connector with an adjustable fastener with the opposed connector being hollow to transport the electrical wiring to the lamp.